Zend_Mail::clearDate PHP Метод

    public function clearDate()
    {
        $this->_date = null;
        $this->clearHeader('Date');
        return $this;
    }

 public function testClearDate()
 {
     $mail = new Zend_Mail();
     $mail->setDate();
     $mail->clearDate();
     $this->assertFalse(isset($mock->headers['Date']));
 }